Electric oven not heat to proper warmth? i went to ladys apartment today and she tell me the oven...

i went to ladys apartment today and she tell me the oven was not heat right..it was set on 250 degree but it was much hotter than that i could detail..i checked the knob to see if it was on wrong but it be fine..i then looked at the component inside stove and that looked ok..any other options out nearby? all burners be good to.
Answers:    unpromising thermostat switch . i believe that there is an adjustment screw on the switch. this join might be of assistance http://www.hometips.com/home_probsolver/...
Thermostat is broke, needs to be replaced. Appliance parts store will hold it. $20-25